Date of Award

Spring 5-15-2016

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Marine Science

College

College of Science

First Advisor

Daniel C. Abel

Abstract/Description

Winyah Bay is a 65-km2 estuary in northeast South Carolina and is considered essential habitat and nursery ground for several shark species of the western North Atlantic. As a result of a number of shark bites/attacks during the summer of 2015, many concluded there was higher abundance of sharks than in previous years. The objective of this study was to test this hypothesis using surveys of shark populations from Winyah Bay in the summer of 2015, and comparing the diversity and abundance of sharks from this survey to those of previous years from the same survey. From July to August in 2002-2006, 2013, and 2015, 169 bottom longlines (16/0 and 12/0 hooks) were set in Winyah Bay. A total of 243 sharks representing 11 species were captured in Winyah Bay. The sandbar shark (Carcharhinus plumbeus), finetooth shark (Carcharhinus isodon), blacktip shark (Carcharhinus limbatus) and Atlantic sharpnose shark (Rhizoprionodon terraenovae) were the most abundant species caught. The average catch per unit effort (CPUE) for all sharks caught in Winyah Bay (1.306, 1.538, 1.706, 1.077, 1.375, 1.545, 1.846, for the periods above) was not significantly different among any of the study years (F = 0.432, p > 0.05, df = 132). However, the proportion of longlines that caught at least one shark (0.722, 0.385, 0.765, 0.538, 0.5, 0.727, and 1.0, for the periods above) was the highest in 2015. Bull sharks accounted for 16.7% of the 2015 total, and the most caught in the period examined for this paper. The prevalence of bull sharks and larger sharks, as well as a high longline index (1.0) could explain the increase in human-shark interactions and could be due to increased water temperatures, the lack of rainfall, or other factors.

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